Method of producing cinematograph



Jan. 14, 1941.

L C. RUDKIN METHOD OF PRODUCING CINEMA'IOGRAPH FILMS Filed Jan. 23, 1939I 4 Sheets-Sheet 1 24 Fzgl.

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A homey Jan. 14, 1941.

L. C. RUDKIN METHOD OF PRODUCING CINEMATOGRAPH FILMS Filed Jan. 25, 1939Y 4 Sheets-Sheet 2 18 INVENTOR Lewis 6. Rudkin 'Jan. 14, 1941. L c.RUDKlN METHOD OF PRODUCING CINEMATOGRAPH FILMS Filed Jan. 23, 1939 4Sheets-Sheet I5 Attorney METHOD OF PRODUCING CINEMATOGRAPH FILMS FiledJan. 2:, 1959 I 4 Sheets-Sheet 4 Fig? Inventor LQMM A tlorney PatentedJan. 14, 1941 2,228,643 I nm'rnon or rnonucmc crmzrm'roc'narn minisLewis Charles Rudkin, Streatham, London,

England Application January 23', 1939, Serial No. 252,496 In GreatBritain January 2'1, ms

' .5 Claims. (Cl. 274-46) This invention relates to methods of andappa-' ratus for recording sound on cinematograph films. Often twoseparate sounds have to bereproduced from a single strip of film. Forexample, in a 5 news reel the sound occuring atthe time .when

the pictures were taken has frequently to be reproduced simultaneouslywith the voice of a com-- mentator, the commentator's remarks havingbeen recorded later than the pictures and. correspond- N ing sound. sofar as I am aware, the two separate sound recordings have always beenmixed,

in such a case, so that, on the master negative and the prints takentherefrom, there is a single variable density or variable area soundtrack con- 15 stituted by the resultant of the two separaterecordings.The gradations of density or the form of the black and white parts inthis resultant have components, due to the two recordings, that aremixed in such a way that the volume of sound 20 due to one recording isreproduced in relation to the volume of sound due to the other recordingin a. predetermined manner, and the resultant track is often such thatone volume at first predominates and then diminishes, whilethe othervolume of sound becomes predominant.

According to the present invention a record of two or more sounds isproduced on a cinemato graph film by printing thereon separate soundtracks representing, respectively, the separate 30 sounds, in parallelto be reproduced simultanecusly. One advantage of this method'is thatone of the tracks may be a variable density track while another is avariable area track. Such tracks cannot be mixed to provide a singleresultant, ex-

35 cept electrically, but there is no dlmc-ulty in re producing soundsimultaneously from the two different tracks in parallel.

The tracks areprinted from tracks already recorded and, veryconveniently, the widths of the,

40 tracks being printed may be varied relativelyto those alreadyrecorded in accordance with the desired relative volumes of soundrequired from the printed tracks at the various points along the lengthsthereof. Advantageously, the printed 45 tracks may lie between parallellines, the perpendicular distance between which is equal to the maximumwidth of the tracks already recorded. Thus, the tracks printed inparallel occupy a width that is no greater than the width of the 50single track that has hitherto, so far as I am aware, always beenprovided, and no special proiecting apparatus is necessary for thecomposite track comprising a number of tracks, usually two, in parallel.55 Where one of the tracks being printed is a variable density track,its width may be varied by adiusting the width ofan aperture to exposemore or less of the width of the associated track which has already beenrecorded. In the caseof :1 variable area track, onthe other hand, itswidth may 5 be varied by adjusting the angle subtended between the planeof the film being printed and the plane of the track that has alreadybeen recorded,

it being understood that, in this particular arrangement, an image ofthe last-mentioned track is projected onto the film being printed. Thisv arrangement'is also suitable for variable density tracks. The width ofeach track being printed may be controlled by a grading strip which iscaused to travel in timed relationship with the film being printed,through the apparatus for effecting the printing. A method of producingthe grading strip is to pass the tracks already recorded throughapparatus enabling the recorded sounds to be heard simultaneously andenabling the relative volumes of the sounds heard to be adjusted, andmoving a cutter, in accordance with such ad-' justment, across a striptraversing the cutter so as to sever from the stripe narrower strip, toserve as the grading strip, having a cam edge.

In order that the invention maybe clearly understood and readily carriedinto effect, certain methods and apparatus in accordance therewith willnow be described by way of example with '30 reference to the'accompanying. diagrammatic drawings, in which:

Figures 1 and 2 are respectively a sectional side elevation and asectional plan of' apparatus forprinting two variable density soundtracks, I'lgure 1 being a section on the line I I in Figure 2, andFigure 2 being a section on the line 11-11 in Figure 1;

Figure 3 is a perspective view of another form of apparatus for use inprinting sound tracks; 40

Figure 4 is a sectional plan showing certainpartsoftheapparatusoi'l'i'gureSy nFigure5isaviewsimiiartollgurehbutshowing one of the parts in anotherposition that it can take up during the operation of the apparatus;Figure 6 is apart sectional plan of a third form of apparatus for use inprinting sound tracks; and

Figure 7 is a perspective view of apparatus for use in controlling theapparatus shown in the preceding figures. Y Y

Referring to Figures 1 and 2, a strip l of.c1ne-- matograph film, whichis to constitute a'master f negative, is drawn oi! a spool 2 and woundupon a u spool 3. The film may already have pictures printed on the pathor space I or it may receive the pictures in a subsequent operation.Between the two spools, the film i passes beneath two films 6 5 and 6bearing positive records of sound tracks and it is from theserecords'that a pair of negative sound tracks I and I are printed on thefilm l. Therecordsonthefilmsi and. arevar iable density tracks; that isto say, the tracks are of constant width and-the sound is represented bygradations at light and shade. The total width of the sound tracks 1 and8', that is to say the distance between the parallel base lines and II,is equal to the width of each of the tracks on the strips and 6 and isthe standard width of a variable density sound track as used in ordinarycinematograph practice. Therefore, to print the two separate tracksbetween the lines I and II, itisnecessarytoexposetothefilm l onlypartofthe width of each of the tracks on the films I and t.Thisisdonebypassingthefilmlbetweenthe film land a plate ii formed with acontrollable aperture l2. Similarly, the film C is passed between'thefilm i and a plate it formed with a controllable aperture ll. As shownin Fig. 2, each aperture is as wide as the distance between the lines 8and ill but is controlled by shutters ii and i8. Now, supposing the meanvolume of sound to be derived from the track 1 is to bear a constantrelation to that derived from the track I, it is only necessary touncover opposite sides or the apertures by amounts such that the widthsof the two tracks being printed give the constant relationship. However,in practice it is often desirable to arrange for one sound to becomedominant, while the other diminishes, and then for the latter sound tobecome dominant. For example, often when music and speech are to bereproduced simultaneously, first one and then the other has to increaseat predetermined points along the length or the film. This is efiectedby moving the shutters i5 and It selectively across the apertures I2 andI4, through the medium of grading strips 11 and it of very thick paperiormed respectively with cam edges "and 2| that act on l'evers 2i and 22connected to the shutters II and Supposing the sound represented by thetrack I is to increase to the maximum possible mean volume, while thesound represented by the track 0 is to fade out completely, the shutterII is moved downwards, as viewed in Fig.2, so as to expose the whole ofthe aperture i! to its associated light source 23. Thus, the whole widthof the record on thefilm iisprinteduponthefilm l andoccupies the spacebetween the lines I and II. A trifle later, the shutter I! is moveddownwardly so as to obscure the whole of the aperture II from itsassociated light source 24.

The cam edges II and Il may be complementary. Then, the width of theexposedpart o! the aperture l2 plusthewidth oftheexposedpart oftheaperture lusaiwaysequ ltotbepernenstdicular distance between the lines land ll.

Thus, the whole space available for sound recordingonthestrip iisalwaysfiliedalthmrghthe tracksland'increaseanddiminishalongthe lengthof the film i.

7 The grading strips l1 and ll traverse rollers 28 and II, on the leversII and 22, in timed relationshipwiththepassageofthefilms Llandovertheapertures "and I4. Thelinearspeedsotthe filmsl,landlare,ofcourse,equal. However.

Tithe gradingstrips i1 and It arerunata lower speed than the film I bothfor the purpose of economy in the paper from which the grading stripsare made, and for the purpose oi avoiding too steep changes in thecontours of the cam edges is and a. 5

To prevent the grading strips l1 and it from twisting as they pass therollers 25 and 26, each grading strip is drawn between the pair ofplates 21 and 2|, the plates 21 and 28 respectively engaging theupperand lower faces of the strips i1 and I8. These plates are formedwith slots 29 that are traversed by the rollers 25 and 26 as they areswung in accordance with the configurations of the cam edges l0 and ill.

The apparatus of Figures 1 and 2 is only suitable i'or printing variabledensity sound tracks but the apparatus 01' Figures 3 to 5 may be usedeither for variable density tracks or variable area tracks. In fact, agreat advantage of the last mentioned apparatus is that it can be usedin the production of a composite sound track comprising variable areaand variable density tracks side by side. A variable area track is, ofcourse, one which, in the negative, is a transparent strip that has oneedge in wave form representing the sound.

In the apparatus of Figure 3, the film 30 being exposed to have soundtracks printed thereon is drawn down from a bobbin II by a bobbin 32driven by an electric motor indicated generally by the reference numeral3!. One of the sound tracks is printed on the filni 30 from a soundtrack on a film 34, which is withdrawn from a bobbin II by a bobbin 3driven by an electric motor indicated generally by the reference numeral31.

A beam or light from a source 30 passes throu the sound track on thefilm I4 and is concentrated on the film It by a lens system indicatedgenerally by the reference numeral 3!. This system-is as tree aspossible from chromatic and spherical aberration and has a long focallength so that, in the operation of the apparatus as described below,the image of the sound track on the film 34- is formed upon the film 30albstantially free from unwanted distortion. The bobbins II and ii arepivotally mounted between arms 40 and ll extending upwardly from aturntable l2 fixed to a vertical spindle 43. When this turntable isturned about the axis A-A of the spindle N, the vertical plane of thefilm 34 is turned relatively 50 to the film I. and to the beam of light.The motor 31 which drives the bobbin 3. is mounted on the turntable 42,so that when the latter is turned the motor 31 moves relatively to themotor 38. It is, however, necessary for the motors 31 55 and II to runexactly in phase and, owing to the relative movement of the motors, amechanical connection between them is not very convenient. Accordingly,the motors II and 31 are induction motors connected to run in accordancewith the well known selfsynchronising system. Thus, the motors haverotors with three phase windings, indicated in Figure 3 by the starwindings 44. The stators (not shown) of these motors are connected to asource of alternating current and are wound to provide a rotatingmagnetic field which serves to rotate the rotors. In order that thelatter may run precisely in phase, the ends of the star windings 44 areconnected. as shown, by condoctors 45 which are connected together byresistances M. The flexibility oi the conductors l5 enables the motor 31to move relatively to the motor II.

Sections through the films I. and 34 appear in Figs. 4 and 5, and thesound track on the film 1s 19 into two parts having complementary camedges.

It is the outer parts severed from the paper strip of Figure '7 that areused as grading strips, the centre part being waste. The loud speaker inthe monitoring apparatus may be replaced by earphones or a meter.

Although the various forms of apparatus par-' ticularly described abovehave been described in connection with the printing of two sound tracks,it will be clear that such apparatus can be extended for printing threeor more sound tracks,'

if desired.

I claim:

1. A method of producing a record of sounds on a cinematograph film,which comprises the steps of printing a sound track on said film byprojecting a beam 01 light through a sound track already recorded on afurther film to cast an image of said track on said first-mentionedfilm, while selectively adjusting the angle subtended by the planes ofone of said two films relatively to the axis of said beam to vary alongits length the width of said track being printed, and printing a furthertrack on said film closely adjacent said first-mentioned track.

2. A method oi producing a record 0! sound on a cinematograph film,which comprises the steps of printing a sound track on said film whilevarying the width of said-track and printing a second track on said filmclosely adjacent said first track while varying the width of said secondtrack, the widths of each of said tracks being controlled along itslength by a grading strip caused to travel in timed relationship withsaid film.

3. A method of producing a record of sounds on a cinematograph film,which comprises the steps of printing parallel and closely adjacentsound tracks on the said film while the latter travels in timedrelationship with grading charts formed with cam edges, and varying thewidths 01! said sound tracks along their lengths in accordance with saidcam edges.

4. A method of producing a record of sounds on a cinematograph film,which comprises the steps of forming a grading chart with a cam edge bysevering said chart from a. wider strip as the latter traverses a cuttermoved to-and-i'ro across said strip in accordance with the relativevolumes 01' said sounds desired during their reproduction, printing asound track on said film while the latter travels in timed relationshipwith said grading chart, varying the width of said track along itslength in accordance with said cam edge, and printing on said film asecond track closely adjacent said first-mentioned track.

5. A method of producing a record oi sounds on a cinematograph filmwhich comprises the steps of printing a sound track on said film byprojecting a beam of light through a sound track already recorded on afurther film to cause an image 01' the track on said first-mentionedfilm, printing a second sound track on said first-mentioned film byprojecting a beam oi light through a sound track already recorded on athird film to cause an image of the second track closely adiacent saidfirst-mentioned image and selectively adjusting the angle subtended bythe planes of said two films bearing tracks already recorded relativelyto the axes of said beams to vary along their lengths the widths of thetracks being printed.

LEWIS CHARLES RUDKIN.

